This post was promoted from YouMoz. The author’s views are entirely his or her own (excluding an unlikely case of hypnosis) and may not reflect the views of Moz.

Keyword data sources have long been a key tool in the pockets of search engine optimizers. There is little argument that know what people search for and how often has and will continue to be an important knowledge set in nearly any SEO endeavor. However, like most things in SEO, the devil is in the data.

The problem

There are myriad keyword data sets available for consumption on the web. More often than not, we need keyword data and predicted search volumes in order to make decisions about content prioritization. The go-to product is normally Google's own Keyword Suggestion Tool, but it leaves much to be desired for those of us who need more data accessible in a programmatic fashion. So, which keyword data sets help us the most in getting keyword data, and how do they differ.

The providers

Virante, the company I work for, has used pretty much every keyword discovery tool or API out there. However, for our purposes here, we have to limit ourselves to providers that give Exact Match Local Search Volume data or estimates. This means we have to ignore one excellent keyword tool out there, Keyword Spy. This also ruled out popular tools like UberSuggest which does not provide search volumes. Finally, I looked only at web services, not standalone keyword tools like MarketSamurai or Xedant. Whenever possible, we used "fresh" data rather than historical indexes.

Please bear in mind that I am just judging the data here. Each of these data sources have tools associated with them that make their data more valuable and in different ways. I will touch on these differences in the conclusions, but understand that I am just judging one feature of the overall offering, not the tools as a whole.

Earlier in May, I reached out to the community to ask for every online keyword data set out there that provided search volumes and here is what I came up with:

Perhaps the most well-known, Word Tracker has a huge database of keywords and their own proprietary search volume data. As a paid user, you can get Google search volume as well powered by SEMRush.

Getting a baseline

The first thing I needed to do was to create a "source of truth" to compare against these data sets. Using the Google Keyword Suggestion Tool, I grabbed the top 100 keywords for each of the DMOZ categories. I think converted their local search volumes into an index from 0 to 100, where 100 is the highest-trafficked term in the list and 0 was the lowest-trafficked term. Finally, I took the LOG of each for visualization purposes. One quick caveat: I am making a big assumption here. Google may report very inaccurate numbers for search volumes. We certainly know they at least round these numbers. However, it is the best I've got for now.

Method 1: Log of indexed search volumes

This most straightforward method of visualizing the differences in the data sets is to look at the comparison of the log of indexed search volumes for each data set. I looked up either by API or by hand the search volumes for every keyword returned via the Google Keyword Suggestion Tool baseline data. From left to right on the graph are the keywords of the highest search volume (according to Google) to those with the lowest.

There were several key takeaways. First, both SEMRush and Grepwords returned a line nearly identical to that from Google. This was to be expected. Unless their data was wildly out of date, it was likely that they would perform best on this type of metric.

A few interesting takeaways:

Wordstream and Keyword Discovery both seemed to track stability with Google data for the top terms, but diverged thereafter.

Keyword Discovery had the most similar trendline to actual Google results of those providers that use their own data sets. However, they also had the lowest keyword coverage.

WordTracker's trendline was actually nearly horizontal, indicating an under-reporting of head terms and over-reporting of tail terms.

Method 2: Average error

I began by putting each of the data sets on to the same 0 to 100 index, where 100 is the most popular keyword and 0 is the least popular. I then subtracted the keyword index values from each of their corresponding Google Keyword Suggestion Tool indexed volumes. This resulted in the following:

Service Provider

Error

SEMRush

<.5

WordStream

6.8

KeywordDiscovery

3.5

GrepWords

<.5

WordTracker

6.8

This doesn't really tell us much more about the performance, simply that SEMRush and GrepWords perform as one would expect, in line with Google's numbers, that Keyword Discovery trends closest to Google and that the error rate for WordStream and WordTracker are fairly similar.

Method 3: Coverage rates

What percentage of keywords are actually found in each index? We know that some indexes are larger than others, but this doesn't necessarily mean that they match up with searches performed on Google. Below are the coverages for the head/mid-tail terms:

Service Provider

Coverage

SEMRush

>99%

WordStream

85%

Keyword Discovery

83%

GrepWords

>99%

WordTracker

95%

It is worth pointing out that even though Keyword Discovery had a lower coverage rate and a lower average error, the average error statistic ignores when words are not present, scoring them as null rather than 0. As expected, SEMRush and GrepWords get high accuracy rates for head and mid-tail keywords. But, upon further examination, we can see that their indexes degrade in coverage as you move down the keyword search frequency scale.

Long-Tail Coverage for Adwords Data Aggregators

Category

SEMRush

GrepWords

Sports Long Tail

86%

60%

Finance Long Tail

90%

87%

Arts Long Tail

49%

68%

As you can see, there are great coverage disparities among long tail for Adwords data aggregators like SEMRush and GrepWords. This is where services like Keyword Discovery, WordStream and WordTracker tend to shine. Because they get their data from sources other than the Adwords tool, they are able to pick up many more variations of keywords that might never show up in a Google Keyword Suggestion Tool query, even though the searches do actually occur on Google.

So which provider is right for which problem?

1. I want obscure, long-tail keywords that are less likely to be found by my competitors.
Keyword Discovery and WordTracker seem to reign supreme here. They have been industry mainstays for a while, but if you want real search and CPC numbers you will need to coordinate with GrepWords or SEMRush. WordTracker actually gives you access to SEMRush data for a limited number of keywords per month.

2. I want as valid of data as possible, so that I can easily compare with competitive metrics.
This is what makes SEMRush one of the most popular tools in the industry. They have a ton of great data.

3. I want data that can easily tie into PPC optimization. WordStream is the clear winner here. Some of their related paid search tools are just killer.

4. I want data fast, accurate, and programmatic.GrepWords appears to be the winner here. One of their API calls allows you return search and CPC data on a thousand words at a time. This is particularly valuable if you are using a tool like Keyword Discovery to get the raw keywords, but want to quickly see if there is Google data to go along with it. Not to mention that their API allows regular expressions for finding related keywords. As of writing this post, they still weren't open for business. Just beta access.

5. I want every possible keyword, period.
You need all of them. It really isn't that terrible of an investment when you are building an initial keyword universe on a large project. While this might mean only keeping accounts open for the first month, more is better. Right?

About russangular —
I am the CTO of Angular. I am married to Morgan, who is frickin awesome, and I have two daughters Claren, Aven and Ellis who are also frickin awesome. We live happily in Durham, NC.Angular is a full service Search Marketing and Analytics Consulting Company.

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Comments
53

Hey, this is Russ. If there are any other keyword services you would like to see me build into this analysis, let me know. The services must provide some sort of exact match search volume metric and have an API. That is about it. Thanks!

New Edit: With the potential loss of the Google Keyword Suggestion Tool, finding a good alternative (unless you want to get a Google Adwords account and use the Planner) will grow in importance.

Very interesting stuff. I'd be curious how Bing volume data (via their API) matches up using your methodology - we've run some analysis in-house. I share your frustration - the toughest part of these analyses is that the only "gold standard" we have is Google, and I've become less and less convinced their public data is reliable. As you said, it's all we've got, but that fact is starting to make me nuts.

Cutts has indicated that there is a lot of sampling bias in industry tools. I have access to the search query #s of about 800K daily searches on Google and they don't match up at all (clearly the data, while accurate, comes from a source that is not representative of the average Google user).

For my purposes, normally the most important thing is relative size. I think it is safe to assume that a keyword with 1000 monthly searches receives more searches than one labeled as receiving 100.

Very nice posy Russ. I wanted to complement you Russ, article is well researched and bases on facts. You put hard efforts in it. Choosing a right keywords is always crucial for any campaign. Is SERPIQ is best tool out there.

Thanks for sharing this list! I often mash-up data from two or three sources whenever I need a list which includes primary, medium and long tail keywords. For e.g Ubersuggest + Keyword Spy + Adwords + SEMRush.

I know the volumes data is missing in Uber but I like the tool as it gives me really good keyword suggestions to start with. And that's why I use other tools in conjunction where I can find the volumes data for these keywords along with other unique ideas to expand my list. This may or may not appeal to all depending upon the accuracy and purpose of data they want.

Unfortunately, I can't simply give out data. I would recommend finding an agency to work with on your campaigns which may currently have subscriptions with many of these providers. One of the benefits of working with agencies (or consultants with a large client base) is they may have tools that simply don't make sense for a single site owner to purchase.

Sorry, I answered this out of order above... Theoretically, if you tracked a large number of keyword every month for a good amount of time, you could assume that the shortest time frame in which the search volume for a keyword changed would be equal to the likely update speed of the tool. However, it is probably not too useful because the update speed has nothing to do with the more important variables like the seasonality of the term, its general volume trends up and down, etc.

Russ, Great blog post here. I would love to for you to check out Zenya's keyword expansion platform as it has some pretty unique features (www.zenya.com). We have categorized keywords in to more that 430K categories and provide advanced filtering options, allowing users to easily manipulate and customize result sets. Feel free to reach out for a free trial of the platform. Cheers!

These are great keyword data sources. I often use Keyword Discovery, Word Tracker and SEMRush. I want to use obscure and long tail keywords so these are great choices for my requirements. Anyway, thanks for sharing the data.

Great rundown of the keyword tool strengths. I've also used and continue to use several tools to get a complete picture. Have you tried SEOCockpit? (https://www.swissmademarketing.com) It is one of my favorite overall tools and I am curious how well it performs on the long-tail side.

You need all of them. It really isn't that terrible of an investment when you are building an initial keyword universe on a large project. While this might mean only keeping accounts open for the first month, more is better. Right?

On this - so theoretically if I didn't want all of the tools at a recurring subscription, I would get all the data I could, dump it into Excel, and then just track rankings on the keywords in the keyword universe?

Exactly. We skip the excel part because we push it directly into a db, but that is the gist. It is particularly useful for doing industry specific volatility (like mozcast) and getting a birds eye view of competitor improvements.

I cannot imagine how much effort/time you have invested in helping produce this fine keyword tools comparison and want to thank you for sharing this. One thing I would like to ask from you is out of the keyword research tools you have analyzed here, any one of them in particular you would recommend for marketers doing international search?

Your research is valuable, you have mentioned some most effective tools out of thousands of tools available, which is enough to say about the dedication. But my concern is very different - most of the keyword tools are based on Inorganic Keywords Research (PPC),which tool is best for Organic Keywords. As i always prefer to analyze the keywords in Google Trends before finalizing them. Is there any more effective way to finalize the most effective keywords ??

We have used all that I mentioned and currently use 3 of the services mentioned above. To be honest, it really does matter what your purposes are (which I tried to give in the conclusions). Most webmasters will get by with Google's Keyword Suggestion Tool, though.